It would have to include more than stock, wouldn’t it? What if someone owns a farm? Or real estate? It seems they couldn’t invest in much of anything under that theory.
My version of a fix :)
When the election is won, the individual reports to the legislators’ barracks for housing. All accounts and funds are frozen. They get up in the morning, eat in the chowhall, get transported to work. Work. Get transported back to the barracks. Eat supper in the chowhall. Go to bed.
Secured grounds. No wandering out at night. No one wandering in.
Serve their time. Then go home and their funds are unfrozen.
Probably don’t want to run for office if married or have kids.